The present invention relates to an apparatus and method for infusing liquids into and to the aspiration of the bone marrow from humans and animals. In particular, the present invention pertains to infusion and aspiration of the bone marrow under emergency and field conditions.
Usually drugs and liquids are delivered to patients through a catheter or intravenously in a peripheral blood vessel. This method is satisfactory in cases where the blood pressure of the patient is at normal levels. However, when blood pressure drops, for example, during a heart attack, drug overdose, or severe hemorrhaging, the peripheral blood vessels collapse and access to these vessels is difficult or impossible. In such cases, an alternative to intravenous infusion is intraosseous infusion. An intraosseous infusion apparatus may be used to infuse drugs and other liquids into the bone marrow under such emergency conditions. In particular, an intraosseous device is used to penetrate the patient""s skin the subcutaneous layer between the skin and the top of the cortical layer of the bone, the cortical layer of the bone, and the bone marrow, and to supply drugs or fluids directly to the blood supply system of the bone. Typically, the sternum, femur, tibia or other bone near the skin is used. Intraosseous infusion can also be used on patients with blood vessels that are hard to find and on young children whose blood vessels are small and also hard to find. Intraosseous infusion can also be used in emergency or battlefield conditions where quick intravascular access may make the difference between life and death. The caregivers in these situations have low levels of training and need an intraosseous device that is simple and rapid to use.
Although intraosseous infusion is a feasible alternative to intravascular infusion, it has not met with widespread acceptance and popularity for a variety of reasons. One reason for this is the practical difficulty in inserting the infusion needle to the proper depth in the bone in order to access the marrow. One method to overcome this problem has been to use a stop or marker on the needle to indicate when the needle has penetrated to a particular depth. This method has not been effective since it requires an estimation of the required depth and careful control during advancement of the needle. Skin and tissue thickness overlying the bone range from 3 mm to 30 mm and thus the skin surface cannot be used as a reliable reference point. A trained individual like a doctor would be needed to determine the correct depth and insert the intraosseous device. This can be difficult even for highly skilled professionals. Another method to overcome this problem has been to monitor the resistance to the penetration of the infusion needle. The resistance is high when the needle goes through the cortical layer of the bone but decreases when it hits the bone marrow. This method is not very effective since resistances may vary. Again, a highly trained individual is required to advance the intraosseous needle or tube slowly and feel for the changes in resistance.
Intraosseous penetration of the cortical layer of the bone to the bone marrow is also needed when a sample of bone marrow from a patient must be taken. Again a needle or tube must be inserted through the subcutaneous layer into the bone so that the bone marrow can then be aspirated. Again, only a highly trained individual can accurately determine the depth of the penetration of the tube or needle into the bone marrow.
In U.K. Pat.No. 1,315,796, issued to Pashenichny et al., a device for intraosseous injection is disclosed consisting of an outer tube with a screw and a male thread on one end and an inner tube fitted into the outer tube. The device is drilled into the osseous tissue, the inner tube is removed and a cannula is connected to the outer tube. U.S. Pat. No. 4,969,870, issued to Kramer et al., discloses an apparatus for intraosseous infusions having a base positioned with its lower surface against the patient""s skin and the infusion tube is pushed through the skin and then rotated to thread through the bone until continued rotation of the tube no longer advances the tube. In both of these devices, there is no automatic depth sensing mechanism. In U.S. Pat. No. 3,815,605, issued to Schmidt et al., an intraosseous device has pins or legs similar to a bone probe that penetrates through the subcutaneous layer. The user releases a compressed spring that exerts a force on and delivers energy to a striker pin to cause it to penetrate the bone. A striker-pin holder that couples the spring to the striker pin, engages a shoulder, which houses the bone probe, thereby limiting the penetration of the striker pin into the bone. Once the spring is released there is no user control over force applied to the striker pin. Thus, if the spring force is insufficient to penetrate the bone cortical the device becomes inoperative. Although this device does have a bone probe which allows the bone cortical layer to be used as a reference point in determining the depth of the penetration of the striker pin instead of the skin, there is no automatic release mechanism to prevent overpenetration of the bone marrow by the coupling member. When the striker-pin holder engages the shoulder, the excess energy released from the spring may drive the coupling member downwardly and over-penetrate the bone.
Other similar apparatus for intravascular infusion (U.S. Pat. No. 5,527,290 issued to Zadini et al. and U.S. Pat. No. 5,480,388 issued to Zadini et al.) and tracheotomies (U.S. Pat. No. 4,556,059 issued to Adamson, Jr.) may have automatic trigger mechanisms that use a spring for self-propelled insertion. None of the prior art discloses a release mechanism that controls the depth of penetration of the penetrating means inserted at arbitrary speed through arbitrary thickness of overlying tissue, against an unknown resistance.
Prior art discloses templates for guiding the insertion of syringes for draining the bursa of the knee and for insertion of spinal marker needles. A template for guiding a caregiver to the correct location for draining the bursa of the knee along with the hypodermic needle used in the process is disclosed in U.S. Pat. No. 5,364,361, issued to Battenfield. U.S. Pat. No. 4,985,019, issued to Michelson, teaches a X-ray marker disc with a grid pattern and indicia for determining the located and orientation of the spinal marker needle. There is a need for a template to guide the placement of an intraosseous infusion apparatus so that a semi-skilled caregiver can accurately and very quickly determine the site of intraosseous infusion.
It should therefore be appreciated that there is a significant need for an intraosseous infusion or aspiration apparatus and a related method that can be used quickly and easily by even low-skilled caregivers in emergency or field conditions. Further there is needed such a device that provides for quick positioning of the target area and one that enables semi-skilled users to reliably and accurately position an intraosseous infusion device. There is also a need for such a device that provides relief from the stress and strain placed on the tubing and protection against dislodgment or overpenetration.
According to the invention, there is provided an apparatus for intraosseous fluid infusion and aspiration of bone marrow beneath a bone cortical layer of a patient. The apparatus has an operative end that refers to the bone penetrating end of the apparatus and a remote end opposite to the operative end. The apparatus has a housing assembly, comprising inner and outer sleeves, a spring assembly, a bone probe assembly, a release mechanism, and a coupler. The housing assembly in operative to receive a force directly applied by a user. The coupler is operative to couple the force applied by the user to an infusion tube such that the force directly applied by the user drives the infusion tube through the bone. The infusion tube may have a bone portal and a hollow flexible tube affixed to the bone portal. The infusion tube infuses fluid to and aspirates tissue from the bone marrow. The release mechanism removes substantially all of the force directly applied by the user on the infusion tube once the bone portal has penetrated the bone marrow a predetermined distance.
The spring assembly is comprised of a spring that is compressed between the remote end of the inner sleeve and the remote end of the bone probe assembly, and functions to hold these two parts in a relative initial position.
The bone probe assembly is slidable into the housing assembly. As a user exerts force onto the housing assembly, the spring compresses and the bone portal penetrates the bone cortical layer. When the housing is withdrawn, the infusion tube is left in the body of the patient with the bone portal embedded in the bone marrow and the hollow infusion tube extending out of the skin.
The housing is, further, comprised of a cylindrical outer sleeve with a ball race in an interior surface at the operative end of the sleeve and a cylindrical inner sleeve which is slidably insertable in the outer sleeve. The inner sleeve has a plurality of ball holes circumferentially spaced in the operative end of the sleeve such that the inner and outer sleeve can be coupled through a plurality of balls located partly in these ball holes and partly in the ball race of the outer sleeve.
Specifically, the bone probe assembly is removably insertable in the inner sleeve. A portion of the outer surface of the bone probe assembly is conical in shape, decreasing in diameter towards the operative end of the infusion apparatus. When a user applies a force to the outer sleeve, the balls couple the outer sleeve to the inner sleeve, which couples the outer sleeve to the infusion tube through a long slender stylet coupled to the remote end of the inner sleeve and over which the hollow infusion tube is mounted. As the user applies force to the outer sleeve, the entire apparatus moves towards the patient and the needles of the bone probe penetrate the skin and subcutaneous layers until they come to rest on the cortical layer. As the user continues to apply force to the outer sleeve, all parts of the apparatus, except for the bone probe assembly, continue to move toward the patient and the bone portal begins to penetrate the cortical layer. Because the bone probe assembly is in contact with the cortical layer and is slidable in the inner sleeve, the bone probe assembly does not move toward the patient. As more relative motion occurs between the bone probe assembly and the rest of the apparatus, the balls start to move down the conical outer surface of the bone probe assembly, and thus move radially inward. When the infusion tube has penetrated the correct distance into the cortical layer, the balls have moved inward until they no longer couple the outer sleeve to the inner sleeve. This action is the release mechanism which releases the outer sleeve from the rest of the apparatus. At this point, any downward force exerted by the user to the outer sleeve, is not transferred to the infusion tube, thereby preventing any further penetration of the infusion tube into the bone.
The bone probe assembly is also coupled to the inner sleeve through pins that engage pin slots in the inner sleeve. The pin slots allow a displacement of the bone probe assembly relative to the inner sleeve that is slightly beyond the displacement at which the release mechanism is activated. The pins are located in pin holes in the annular band of the bone probe assembly adjacent to the remote end of the conical surface down which the balls travel as the release mechanism is activated. A bone probe ring is adjacent to the operative end of the conical surface. From the bone probe ring, a plurality of needles project out in a circle.
Furthermore, the bone probe assembly has an axial opening. In the axial opening there may be an infusion tube surrounded by two support sleeves and mounted on a stylet attached to the inner sleeve and passing through the infusion tube and contacting a bone portal. The support sleeves brace the infusion tube and stylet when a force is applied to the outer sleeve. The stylet transfers user applied force to the bone portal to cause it to penetrate the bone.
There may be additionally provided an elongated remover in the shape of a rod that has threads at one end. After an infusion is complete, the remover is inserted into the infusion tube so that it engages the threads in the bone portal. A force is applied to the remover in the direction away from the bone thereby extracting the bone portal from the bone.
In another aspect of the invention, a method for using the intraosseous infusion and aspiration apparatus may comprise using the template patch to quickly locate the site of infusion by first identifying a key anatomical feature of the bone to be penetrated. The peripheral notch of the template patch is aligned to this feature so that the target zone is over the desired area of penetration. An intraosseous fluid infusion and aspiration apparatus may be introduced to the target zone by pushing on the outer sleeve of the apparatus with sufficient force so that the bone portal is inserted into the bone marrow to a predetermined depth. The apparatus may be pulled out after the release mechanism is heard or felt and leaves behind the infusion tube and the bone portal in the bone. An external tube may be connected to the infusion tube and then clamped to the tube clamp located on the template patch to lessen the strain on the infusion tube or, the infusion tube may be clamped directly in the tube clamp. A covering may be placed on the template patch to protect the infusion site. After the infusion is complete, the bone portal and infusion tube may be removed with a remover that engages the bone portal.
In another aspect of the invention, a release mechanism is provided. This release mechanism is designed to control the distance over which a user exerted force can act. The displacement of the bone portal relative to the bone is always identical regardless of the speed at which the force is exerted by a user, regardless of whether the force exerted is constant or variable, and regardless of the magnitude of the force exerted on the bone portal. This is in contrast to a spring trigger mechanism where the apparat us is propelled forward by a fixed quantity of energy stored in a spring but the distance propelled cannot be accurately controlled because the fixed amount of energy stored in the spring may be either inadequate to puncture the bone, or may be too much, resulting in overpenetration of the bone.
In another aspect of the invention, the intraosseous infusion and aspiration apparatus may be optimized for infusion and aspiration of different bones with different bone resistances, different overlying skin and subcutaneous resistances, and different depth of penetrations by modifying several variables. The spring constant, the attributes of the bone probe needles, the axial displacement of the balls, the angle of the conical surface on the bone probe assembly, the angle of the ball contacting surface on the outer sleeve and the size of the pin slots may be adjusted to yield different bone penetration depths, different maximum penetration depths, different applying forces, and different maximum applying forces that would be needed for different bones.
Accordingly, the present invention is embodied in an intraosseous infusion and aspiration apparatus and related method which effectively allows a user to place an infusion tube in the bone marrow of the patient without having to estimate the penetration depth or bone""s resistance to penetration and without having to estimate the target area of the placement of the infusion tube. Essentially, the present invention provides an object to be positioned, an outer sleeve to push on, a coupler to couple the outer sleeve to the object being positioned, a position probe that senses the location of the object to be positioned relative to a reference point and a release mechanism that removes substantially all of the force applied to the object, once the object is correctly positioned relative to the reference point. More specifically, the object being positioned is the infusion tube, the coupler is the balls, and the position probe corresponds to the bone probe assembly.